The background description provided here is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
Internal combustion engines combust an air and fuel mixture within cylinders to drive pistons, which produces drive torque. Air flow into the engine is regulated via a throttle. A fuel control system adjusts the rate that fuel is injected to provide a desired air/fuel mixture to the cylinders. Increasing the amount of air and fuel provided to the cylinders typically increases the torque output of the engine.
Turbochargers are used to increase the efficiency of internal combustion engines by forcing additional air into the cylinders. Turbochargers include a turbine and a compressor. The turbine is driven by exhaust gas produced by the engine and, in turn, drives the compressor using the power of the exhaust gas. The compressor then compresses air entering the cylinders to force more air into the cylinders. The amount of boost (the amount of intake air compression) provided by a turbocharger is typically controlled by adjusting the position of a wastegate that allows exhaust gas to bypass the turbine. The amount of boost provided by a variable geometry turbocharger is controlled by adjusting the position of vanes within the variable geometry turbocharger.